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# AstraZeneca Covid Vaccine has 79% Efficacy
- URL: https://www.fdaweb.com/astrazeneca-covid-vaccine-has-79-efficacy/
- Published: 2021-03-22T12:00:00.000Z
- Updated: 2026-09-14T16:51:43.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5148928

AstraZeneca is likely weeks away from seeking an FDA emergency use authorization for its Covid-19 vaccine after reporting interim data from a U.S. Phase 3 trial showing efficacy of 79% at preventing symptomatic Covid-19 and 100% efficacy at preventing severe disease and hospitalization. The [company said](https://www.astrazeneca.com/media-centre/press-releases/2021/astrazeneca-us-vaccine-trial-met-primary-endpoint.html?ref=fdaweb.com) vaccine efficacy was consistent across ethnicity and age groups, and the trial’s independent data safety monitoring board identified no safety concerns related to the vaccine. While concerns about blood clots have dominated the news based on reports in areas around the world where the vaccine is already marketed, the safety board conducted a specific review of thrombotic events and found no increased risk among the 21,583 participants receiving at least one dose of the vaccine in the U.S., the company says.

The trial included two doses administered at a four-week interval. “Previous trials have shown that an extended interval of up to 12 weeks demonstrated greater efficacy, which was also supported by immunogenicity data,” AstraZeneca says. “This evidence suggests administration of the second dose with an interval longer than four weeks could further increase efficacy and accelerates the number of people who can receive their first dose.” The vaccine can be stored at normal refrigerated conditions for at least six months and administered without the need for preparation within existing healthcare settings, it says.